Shock absorber



G. J. KOEHL SHOCK ABSORBER April 9, 1935.

'Filed Ooi. 8, 1930 Patented Apr. 9, 1935!4 UNITED STATES PATENT OFFICE SHOCK ABSORBER George J. Koehl,

Application October 8,

2 Claims.

My invention relates to shock absorbers, and

the objects of my invention are: y

First: To provide a shock absorber which is particularly adapted for use yin connection with airplanes, in such cases forming a strut of the landing gear;

Second: To p rovide a shock absorber of the hydraulic type in which leakage of fluids from within is reduced to a minimum;

Third: To provide a shock absorber in which 'the amount of expansion and contraction in its length may be lrelatively great for its over-all length, thereby providing a shock absorber which cushions extreme shocks due to poor landings, and reducing the strain on other parts ofthe airplane; l

Fourth: To provide a shock absorber yin which the resistance to movement may be varied to suit the weight of various airplanes and the uses to which they are put;

Fifth: To provide a shock absorber of this type, which, after once being assembled, may be adjusted entirely from the outside thereof;

Sixth: To provide a shock absorber of thisclass having relatively few parts, all of which may be light of construction;

Seventh: To provide a shock absorber which offers low parasite resistance;

Eighth: To provide a novel means of sealing the joints of this type of shock absorber; and

Ninth: To provide on the whole a novelly construct'ed type of shock absorber which is simple of construction proportional to its functions, durable, eicient in its action, and which will not readily deteriorate or get out or order.

With these and other objects in view as will appear hereinafter, my invention consists of certain novel features of construction,` combination and.

arrangement of parts and portions as will be hereinafter described in detail and particularly set forth in the appended claims, reference being had to the accompanying drawing and to the characters of reference thereon, which form a part of this application, in which:

Figure l is a longitudinal sectional view of my shock absorber with parts and portions shown in elevation to facilitate the illustration; Fig. 2 is an enlarged transverse sectional view through 22 of Fig. l; Fig. 3 is another enlarged transverse sectional view on line 3-3 of Fig. 1; Fig. 4 is an enlarged transverse sectional view through 4 4 of Fig. l; and Fig. 5 is a still further enlarged fragmentary longitudinal sectional View through 5-5 of Fig. l, with the piston rod in its extreme outer position relative to the cylinders.

Similar characters of reference refer to similar parts and portions throughout the several views of thedrawing.

Cylinder I, piston rod 2, piston rod bearing 3, locking ring 4, channel ring sealing washer 5, se-

San Diego, Calif.

1930, Serial No. 481,107 (c1. 2cv- 65) curing ring ii, packing 1, drain valve 8, piston` 9, upper sealing washer I0, Washer II, nut I2, deiiecting dome i3, nut I4, lower sealing washer` I5, washer retaining ring I6, washer retainernut I'I, and air supply tube I8, constitute'the principal parts and portions `of my shock absorber.,

A relatively long cylinder I is provided, having a dome-shaped closed upper end la; Extending upwardly from this upper end is a iitting Ib arranged to'attach to a vsuitable portion of an airplane, not shown. The dome-shaped end la is fitted with an air valve Ic, which may be in the form or a check valve similar to the type used for automobile tires.

' A piston rodY is provided which extends into the cylinder through the lower or open end thereof. The piston rod is centered relative to the cylinder I by means of a piston rod bearing or sleeve 3. The sleeve 3 is iittedinto the lower or open end of the cylinder l, and is wedged in such relation by` a locking ring 4,which,1its around corresponding iianges ld and 3a ofthe cylinder I and piston rod bearing 3. l.

The lowerportion of the bearing 3 comprises the'bearing portion which snugly receives the piston rod 2. Above the bearing portion 3b the bore of the bearing 3 is increased in diameter.

The portion of the increased bore of the bearing` 3 contiguous to the bearing portion 3b forms with the piston rod 2, a packing receiving channel 3c, which is substantially wedge-shaped and open toward the inside of the cylinder I. Above the packing receiving channel, the bore is further enlarged forming a shoulder 3d extending radially outwardly from the open end of the channel 3c. This shoulder 3d is thebase of a sealing Washer receiving channel 3e, the inner wall of which is the piston rod 2. A

A sealing washer 5 in the form of an annular channel with upturned side Walls 5a and 5b lits in the channel 3e. The base portion of the seal? ing washer connecting its side walls 5a and 5b is secured to the shoulder 3d by a securing ring 6 having screws @a yextending therethrough and into the material of the bearing 3. `The innerportion of the sealing washer including they inner side wall 5a extends over and closes vthe .open or inner side oi the packing receiving channel3c. The inner side wall 5a yieldably bears against the piston rod 2 and is beveled so that its inner surface converges upwardly or towards the interior of the cylinder I. This causes the inner. side wall or sleeve 5a to increase its pressure against the piston rod with increased pressure within the cylinder I The channel 3c-is lled with*V packing-1. VPresg sure from within the lower chamber, designated A, of the cylinder causes the portion of the sealing washer overhanging the packing chamber 3c to increase its pressure against the packing and Va piston 9. 'Ihe piston 9 is in the form of a hollow cylinder closed at its upper end by ahead y9a. The piston rod 2 extends within the piston ,Q and is Vattached to its head 9a. l

.Extending upwardly from the head 9a of the piston is a threaded shank portion 9b which is co-axial with the piston rod 2. Fitted over the shankSb and resting againstY the head'Sa, is a cup-shaped upper sealing washer I0, the walls or Vskirt Illa of which extend upwardly and engage the inner walls ofthe cylinder I. The central 'portion'of the upper sealing washer I0 is held in position by a washer I I and nut I2. Y

, Also tted over the shank 9b, is a deflection dome I3, which is in the'form of a spherical segment. A nut I4 fits over the dome I3. The dome I3 is of a large enough diameter to' bear against the margin ofthe washer I 0, adjacent the upturned rim or skirt thereof, so that when the Vnut I4` is tightened down, pressure isvevenly distributed around theV margins of theV sealing washer. The dome I3 greatly increases the radial pressure outwardly against the skirt Illa, soas to hold it firmly against the inner'wallsrof the cylinder I, and VeifectV a tightly sealed joint therewith; 1

The lower end of the piston 9 is provided-with an internal flange 9c, against theV under surface of Vwhich is secured thering portionl 15o of a lowerV sealing washer l5. Extending from the outer periphery Yof the ring portion downwardly along the inner walls of the cylinder I is a skirt portion I5b'. i Y

, The ring portion I5va is held against the flange 9c4 by a 'rim' portion, designated I6a,`of a retain- Ying Vring I6. Extending radially inwardlyt'from therim portion I6a are aV plurality of webs IBb, which join to a hub portion I6c adapted to lit around the piston rod 2. The slots or openings, designated I6d, formed between the iwebs I6c connect the chamber A' with the chamber designated AI, inside the piston.

` 'I'he hubportion I6c is'adapted to be engaged o n'itsunder side by a retaining nut I I, which screws onto a threaded portion 2a of the piston rod, as shown best in Figs. 3 and 5.

The piston rod bearing 3 is'provided with an annular stop portion 3f, which extends upwardly provided therein'witha small tube I8, which communicates with a portion AI ofthe chamber A withinA the piston Y9. The other end of the tube I8 protrudes from the extended portion of the piston rod 2, and is provided with a suitable check valve I8a.

The lower endV of the piston rod 2 is provided y. with lasuitable fitting 2b, which is adaptedlto connect with other portions of the landing gear,

nots'hown.

'I'he shock absorber is prepared for operation as follows:

Suitable oil is rst forced in the valves I c and B, until the sealing washers I0 and 5 are well covered. Airis then pumped into valve I c and in the valve Ia, `filling both `upper, chambers, designated B, and the lower chamber A, with air under pressure.

The limit of pressure in the two chambers is adjusted so that when the strut is in position supporting a Weight, pressure in the upper chamber B is greater than that in the lower chamber, as, for example, the pressure in the upper chamber may be lbs. per square inch, While the pressure in the lower chamber is about 60 lbs. per square inch. y The difference infthese pressures, or 40 lbs., equals the cushioned pressure of the shock absorber.V Of course, the pressures within the shock yabsorber vary with different airplanes.

`By reason ofthe arrangement of the sealing A20 washer 5 and packing 1, it is extremely diicult for the pressure in the chamber A to be lost through the connectionbetween the piston rod and its bearing, although the piston rod is slidable. Furthermore, the shape ofthe deflection dome I3, by causing an increased radial shock force againstithe skirt of the upper washer I0,

kmore vtightly seals the joint between the piston and the cylinder so that the relative quantities of air in the two chambers A and B maintained. y

It is obvious from the construction as illustrated in the drawing and described inthe foregoing specifcation that there is provided a shock absorber as aimed at and set forth in the objects of the invention, and though I havevshown and described a particular-construction, combinationl ends of said piston, a piston rod joined to said 7 piston extending from one end of said cylinder,V

sleeve means closing the one end of said cylinder and slidably receiving said piston rod, said Vpiston dividing said cylinder into an upper and lower chamber and both liquid and air under pressure above atmospheric in both of said chambers, and means for introducing air into both of said chambers near the upper end thereof. ,i

' 2. In a shock absorber, a cylinder, an'elongated cup-shaped piston hollow from end to end reciprocally mounted therein, sealing means at both ends of said piston, a piston rod joined to said piston extending from one end of said cylinder, sleeve means closing the one end of said cylinder and slidably receiving said piston rod, said piston dividing said cylinder into an upper and lower chamber and both liquid and air under'pressure above atmospheric in both of said chambers, and means for introducing air into bothof Vsaid chambers near the upper end thereof, the means for introducing air into the. lower chamber extending through the piston rod from the extremity of said cylinder. t

GEORGE J. KOEHL- are 

